How long have you been an enthusiast of the Mopar brand? Has it been since the ’80s, ’70s, ’60s, or even earlier? If so, you remember the days when Mopar owners were treated like the red-headed step children of the automotive aftermarket (no offense to our readers who are actually red-headed step children, it’s just a saying). In fact, for many years Mopar owners had to deal with sluggish support when it came to high-quality performance parts for their cars and trucks, while off-brand owners enjoyed a plethora of support for their cars and engines. Times have changed, however, and now owners of Mopar big-block, small-block, and Hemi powered vehicles can purchase an abundance of performance parts to enhance the performance of their cars and trucks.

2/18<strong>01</strong> We’ve come a long way with our C-Body project, and our ’69 Newport convertible is driving nicely with new suspension, tires, and brakes, and stays drier now that we’ve replaced the top. We’re also making headway on the 383 in our Chrysler, and this month we’ll install Edelbrock’s E-Street cylinder heads to improve power and torque.

One of the biggest aftermarket supporters of the Mopar brand has to be Edelbrock Performance. Edelbrock was the first company to provide economically priced, great performing aluminum cylinder heads for Chrysler big-blocks and small-blocks, and we see more cars at events and races sporting Edelbrock Performer RPM heads than any other type of aftermarket head. Edelbrock also has a full line of intake manifolds, carburetors, and other performance goodies for Mopar engines, all of which can improve the power, performance, and looks of your ride. We know from our testing that the Performer RPM and Victor big-block heads can help achieve great power, so when Edelbrock introduced their E-Street line of heads for the big-block, we wanted to be the first to test them.

3/18<strong>02</strong> In previous issues of Mopar Muscle, we installed tti headers and exhaust, a Comp hydraulic flat-tappet cam and lifters, and an Edelbrock Performer RPM intake and 750-cfm Performer series carburetor. Our stock, low-compression 383 was low on power when we started, but these modifications helped us achieve respectable power numbers.

Edelbrock’s E-Street cylinder heads are designed as a bolt-on replacement head for non-emissions 1961-1978 Chrysler B and RB series big-block engines. The assembled E-Street heads are available in two different part numbers, 5090 and 5093 offering combustion chamber volumes of 75 and 84 cc’s respectively. Other than chamber volume, the specs for the E-Street heads are identical, with 210cc intake ports and 70cc exhaust ports, and swirl-polished stainless steel valves. Intake valves are 2.14-inch, and exhaust valves measure 1.81 inches, both with undercut stems for improved flow. Edelbrock installs their PN 5792 Sure-Seat valve springs on these cylinder heads, and the heads can handle camshafts with lifts up to .600 inch.

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These cylinder heads are assembled with all new parts, including Edelbrock’s PN 9644 machined steel retainers, PN 9616 locks, and PN 9644 valve spring seats. Two-ring positive control oil seals are installed on the valve stems, and all of the provisions for the intake manifold, exhaust headers, rocker arms, and accessories are in the factory locations, for a true bolt-on installation. Additional benefits of the E-Street heads are dry, Heli-coiled exhaust bolt provisions, and spark plug provisions that are angled 15 degrees for more efficient combustion. The 383 we’re testing these heads on is equipped with a low compression ratio of only 8.37:1, so we decided to order the 75 cc chamber heads to increase the compression of our engine.

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Compression ratio is an important factor when it comes to power, and with such low compression, the 383 in our Chrysler Newport isn’t what we’d consider a performance engine. We have already made improvements to our engine in previous articles, installing a Comp hydraulic flat-tappet camshaft and lifters, Comp double-roller timing chain and gears, Edelbrock Performer RPM intake, 750 cfm Edelbrock Performer series carburetor, and tti headers and exhaust. The details of these installations can be found in previous issues of Mopar Muscle, and netted improvements of some 33 horsepower and 27 lb-ft of torque at the rear wheels.

6/18<strong>03</strong> After our previous modifications, our 383 made 245 horsepower and 315 lb-ft of torque at the rear wheels. This is up substantially from our baseline of 212 horsepower and 288 lb-ft of torque, but we knew we could make more improvement with a cylinder head swap.

By replacing the factory 906 heads on our 383 with the E-Street aluminum heads, we’ll see several immediate benefits, including a 40-plus pound weight reduction from the front of our already heavy Chrysler convertible. Additionally, the smaller 75 cc combustion chamber will increase the compression of our .030 over 383 from 8.37:1 to 9.38:1, over a full point. 9.38:1 compression is still not what we’d consider high, but at least we’re going the right direction in terms of performance. The closed combustion chambers with angled spark plugs will also improve combustion efficiency, further adding to our engine’s performance potential.

The E-Street heads will also offer flow improvements over our 906 castings. The 906 heads on our 383 have a little bit of match-porting and bowl work done, but the E-Street heads provide better flow and an improved combustion chamber, equaling enhanced performance, right out of the box. In applications with a larger than stock camshaft, like ours, Edelbrock recommends installing adjustable rocker arms rather than using the factory, non-adjustable units. Comp Cams Pro-Magnum rocker arms are a great choice, offering a lot of benefit for the cost, so we ordered a set of their PN 1621-16 roller rocker arms for our big-block. We also ordered Edelbrock’s PN 8591 head bolts, a pair of Fel-Pro PN 1009 head gaskets, and a PN 1214 intake valley gasket to complete the installation.

The E-Street heads install just like factory cylinder heads, and the head bolts are installed and tightened in the standard sequence to a final torque of 70 lb-ft. Edelbrock recommends checking piston-to-valve, piston-to-head, and valve-to-bore clearances, and we found all of our measurements to be adequate. The Edelbrock instructions are very complete, and detail all of the issues you could encounter during installation. With the heads in place, we installed our Comp Pro-Magnum rocker arms and used a checking push rod to measure pushrod length. The Pro-Magnum rockers use ball/ball style pushrods, and ours measured 83⁄8 inches. After measuring, we ordered the Hi-Tech pushrods from Comp and got busy installing the intake, exhaust, and spark plugs on our engine.

Even though the E-Street heads use a spark plug angle of 15 degrees, they will work with most factory and aftermarket exhaust manifolds and headers. The tti headers we installed in a previous article offered plenty of clearance, and our factory replacement plug wires with 90 degree boots posed no installation issues. Remember that with aluminum heads, anti-seize compound must be used on the threads of the spark plugs to protect against dissimilar metal corrosion.

7/18<strong>04</strong> Edelbrock’s new E-Street aluminum cylinder heads are a direct replacement for Chrysler big-block cylinder heads, and bolt right in place. The provisions for the intake, exhaust, rockers, and accessories are all in factory locations, making installation easy.

8/18<strong>05</strong> The E-Street heads are available with two different chamber sizes, 84cc and 75cc like the ones shown here. The combustion chamber offers plenty of quench area, and the spark plugs are angled 15-degrees toward the exhaust valve for more efficient combustion.

11/18<strong>07</strong> E-Street heads are assembled with all new parts, including Edelbrock’s Sure Seat valve springs, and positive control oil seals. Out of the box, these cylinder heads are set up for flat-tappet camshafts with lift up to .600 inch.

12/18<strong>08</strong> Side by side, the E-Street heads are lighter by more than 40 pounds per pair. The 906 heads we removed have an open, inefficient combustion chamber. Modern technology gives the Edelbrock heads many advantages when compared to factory Chrysler castings, including hardened valve seats compatible with unleaded fuel.

The Edelbrock heads require 14mm by ¾-inch reach reach spark plugs (long-reach), which are different than factory short-reach plugs, so you’ll have to buy new plugs when installing these heads. We picked up a set of Autolite 3924 plugs at the local auto parts store for our application. Remember that spark plug heat range requirements depend on the cylinder pressure of the engine, and the general rule of thumb is the hotter the engine, the colder the plug. Our engine isn’t all that hot with just over 9:1 compression, so we chose spark plugs on the colder end of the range.

After installing our pushrods and setting valve lash at zero plus one turn for our hydraulic lifter application, we topped our heads with a set of Edelbrock’s stamped steel, logo valve covers for a clean look. With the installation complete, we turned the key and fired up the 383 to check for leaks. Our engine ran great and seemed crisper when we opened the throttle, so we were eager to see what kind of improvement the E-Street heads would net. Our preliminary test drive was encouraging, and we could definitely tell that the 383 in our Chrysler was making more power and torque. With no problems after a local test drive, we took the big Chrysler over to our shop in Tampa, Florida, to strap it onto the Dynojet chassis dyno.

Installing new parts on your Mopar is great, especially when you can feel the difference in the seat of your pants. Taking your car or truck to the track is a fun way to track performance improvements as well, but the best way to measure how much power and torque your engine is making is on an engine or chassis dyno. Engine dyno’s are an excellent way to measure the true, unrestricted horsepower and torque that an engine makes without the parasitic drag of engine accessories or a drive train, but a chassis dyno measures the true power that is transferred to the rear wheels of the vehicle.

When we started this project, our Chrysler made a pitiful 212 horsepower, and 288 lb-ft of torque at the rear wheels with its stock, low-compression 383 and exhaust manifolds. By installing tti headers and exhaust, a mild hydraulic Comp cam and lifters, an Edelbrock intake, and Edelbrock carburetor, we improved our 383’s output to over 245 rear-wheel horsepower and more than 315 lb-ft of torque. Testing our car after installing the Edelbrock E-Street cylinder heads, horsepower climbed to over 276.06 and torque was up by some 20 lb-ft to 335.44 lb-ft at peak. At areas below peak, we made substantial gains as well, meaning our engine will pull harder throughout the rpm range and really get our big Chrysler moving.

Any time you evaluate numbers from the chassis dyno, you need to remember that these numbers are substantially lower than power and torque at the flywheel. On the chassis dyno, the engine is turning accessories like the alternator, power steering pump, water pump, and air conditioning compressor drive, and power losses through the torque converter, transmission, differential, and full exhaust system can all be substantial. What we can tell you for sure, is that our Chrysler is much more fun to drive now and pulls harder whether accelerating from a standing start or passing someone at highway speeds. By installing the E-Street heads our mild 383 gained over 30 horsepower and 20 lb-ft of torque, showing clear improvements over the factory 906 castings. On a larger displacement, higher compression engine, we’d expect even higher gains. mm

13/18<strong>09</strong> Due to their design, special head bolts are required and available directly through Edelbrock. Using new gaskets, we installed the heads and tightened the head bolts in three steps to a final torque of 70 lb-ft.

14/18<strong>10</strong> With stock camshafts, the factory Chrysler stamped steel rocker arms can be used with the E-Street heads. With higher than stock lift camshafts, Edelbrock recommends adjustable rocker arms. We ordered a set of Ultra Pro-Magnum rocker arms from Comp Cams to install on our 383. Comp’s 1.5 ratio Pro-Magnum rockers offer a roller tip, are bushed where they ride on the rocker shaft, and a cup-style adjuster on the pushrod end. We also ordered a set of Comp’s Hi Tech pushrods with ball-ball ends and installed them with the rockers, setting valve lash at zeto plus one turn for our hydraulic lifters.

15/18<strong>11</strong> The Edelbrock E-Street heads require long-reach spark plugs, and because the heads are aluminum, anti-seize compound must be applied to the threads to prevent corrosion. Without anti-seize, dissimilar metal corrosion can lock the plugs in the heads, causing stripped threads or broken plugs when you attempt to remove them.

16/18<strong>12</strong> With the heads and rocker arms installed, we re-installed our intake, and headers using new gaskets. We topped our new heads with Edelbrock’s Signature Series valve covers, and fired up the 383 for some initial drivability testing. Our initial impression was favorable, and the engine sounded crisper with noticeably more power.

17/18<strong>13</strong> As the saying goes, the dyno doesn’t lie. With our big Newport strapped to the Dynojet chassis dyno, we confirmed our seat of the pants impression. Power and torque were both up significantly, and improvements were seen throughout the rpm range.